Railway-traffic-controlling apparatus



Nov; 30 1926. 1,609,140

H. A. THOMPSON RAILWAY TRAFFIC ONTROLLING APPARATUS voriginal Filed A gust 5, 1924 INVENTOR} Patented Nov. 30, 1926.

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rea ies ,HOW'ARD A. THOMPSON, :OF EDGEWOOD, PENNSYLVANIA, ASfdIGNOItTO THE UjlllQN SWITCH,& SIGNAL COMPANY, 015 SWISSVALE. PENNSYLVANIA, A CORPORATION "OF PENNSYLVANIA.

RAILWAY-TRAFFIC CONTROLLING AIE'FAEATUS.

Application filed August 15, 1924, Serial No..732,196. Renewed October 21, 19 25.

My invention relates to railway traffic controlling apparatus, and particularly to apparatus of the type comprising a track relay responsive to a difference of potential between the track rails.

One-feature of my invention is the provision of means for maintaining substantially constant the voltage applied to such relay when said potential varies.

I will-describe oneform and v arrangement ofuapparatus embodying my invention, and will then point out the novel features there- .Qf c aims.

The accompanying drawing is a view, partly diagrammatic and partly inperspective, ,showi ng one form of railway traffic controllingappar-atus embodying my invention.

characters 1 and l designate the track rails of. a stretch of railway track. over whichthe .traffic moves in both directions. A track section 'A&B is separatedfrom the rest of the stretch by meansof insulatedjoints 2.E2

interposed 'in the two track rails.

jThe sectionA- B is provided withtrackway cjircuits intendedfor co-operation with .tnain carriedggoverning means responsive to ,t11e;pr esenc e of alternating. current in the track rails. Since such governing apparatus is usually controlled by the trackway cur-rents through the medium of suitable re- [ceiving apparatus carried on the train in advance of the forward axle, and since trains proceedinboth directions over sec- ,tion A fl3, it 'followsjthat means must be provided -for supplying the track section with,,alternating current at each end of the section. I accordingly provide thesection with two track-transformers T and T located at the left hand an d right hand ends, respectively, ofthe section and, each having a. secondary windinga constantly connected across the rails at the adjacent endof the section. ,An impedance 3 is interposed between the secondaryl l of each track trans- .for-Ine1'-,and oi1e rail l of theiassociated sectransformer T.

trolled that the relay is normally de-energized, but isenergized when a train moving from right to left enters section AB and is retained in the energized condition as long as the'train occupiesthe section. As shown in the drawing,'relay S is ole-energized and under these conditions transformer Tis deenergized but'transformer T is energized, its primary winding 5 being connected, over back contact 68 of relay 'S, with terminals J and'K of a suitable source of alternating current not shown in'the drawing. "\Vheln relay S is energized, transformer T is deenergized but transformer Tfis then supplied with current from terminals J and'K thus be plainthat when section AB is occupi'ed by a train moving from left to right [Referring to the drawing, the reference or is unoccupied, alternating current is supthat when the section is oceupie'd by a train moving from right toleft the alternating current is supplied to the rails by transformer T.

Section A B is further provided wit-ha track relay R arranged-to receive energy from the track rails at a point adjacent Due to the impedance of the trackrails, and to the'leakage through .the track ballast, the difference of potential between the rails of the section A 13 at point A willbe considerably greaterwhen the section is being supplied with alternating current from transformer "T than when transformer T is supplying the current to the section. In the absence of any preventative means this widely varying difference of potential would be applied to the terminals of the relay and might damage it.

This condition isundesirable and I thereforeprovide a regulating transformeryD to maintain substantially constant the voltage applied to the relay irrespective of varia tions in the difi'erence of potential between rails at point A. This transformer J) cornprises a continuous magnetizable cor-e 9.having a first leg 11 vcarryingacprimary winding 15 connected across'the rails adjacent point A. Opposite to leg 11 is a second leg 10 so designed and proportioned that for normal values of potential difference between rails at point A', that is, when .transformer T is energized, the leg 10 is magnetically saturated. The transformer D also comprises a magnetic leakage member 12 of magnetic material which member forms a shunt around leg 11 of core 9. i The member 12 is separated from the core 9 by two air gaps 13 and 13 and carries a secondary winding let. A portion of the flux created by winding 15 threads winding 1 1 and induces therein an electron'iotive force. Secondary winding 14 is connected in series with relay R, and the relay and winding 1a are in turn connected across winding 15 in such manner that the voltage induced in winding let is opposed to the voltage applied to winding 15 from the track rails.

The parts are so proportioned that when section AB is supplied with alternating current from transformer T the voltage across relay R is of the proper value for operating relay R and the magnetic flux in core 9 is of such value that leg 10 is saturated. Then if the voltage across the rails at point A increases, as by the energization of transformer T, the increased potential difference between the rails at point A causes an increase in the current through winding 15 which results in an increased flux through leg 11. Leg 10 is, however, saturated and so the larger part of the additional flux threads through member 12 thus increasing the volt age induced in winding 14. Since this voltage opposes the voltage supplied from the rails, the result is that the increase in difference of potential effective at the terminals of the relay is less than the actual increase in the difference of potential between rails.

The ratio of turns in windings 15 and 1 1 is so chosen that a given increase in voltage applied to winding 15 causes an equal increase in the voltage induced in winding 14. WVith this arrangement it is plain that the voltage applied to the terminals of relay R is substantially constant over a wide range of variation in the potential difference between rails.

The relay B may be used to control apparatus not shown in the drawing, such as a trackway signal, in any desired manner.

I do not, in the present application, make any claim for the broad combination of the transformer D with any source of current and any electro-responsive device, such in vention being claimed in my co-pending application filed on the 13th day of February, 1925, Serial No. 8918, for voltage regulating apparatus.

Although I have herein shown and described only one form and arrangement of railway traffic controlling apparatus embodymg my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a section of railway track, a track relay connected across the rails of said section, means for creating an alternating difference of potential across the rails of said section, and a transforn'ier for maintaining the voltage across said relay substantially constant when said difference of potential is varied, said transformer having a secondary winding connected in series with said relay and a primary winding connected in parallel with said relay.

2. In combination, a section of railway track, a track relay connected across the rails of said section, means for creating an alternating difference of potential across the rails of said section, and a transformer for maintaining the voltage across said relay substantially constant when said difference of potential is varied, said transformer having a secondary winding connected in series with said relay and a primary winding c011- nected in parallel with said relay and said secondary winding.

3. In combination, a section of railway track, a track relay connected across the rails of said section at a point, means for creating an alternating difference of potential between the rails of said section the magnitude of which difference of potential is variable at said point, a continuous magnetizable core having a first leg carrying a primary winding connected in parallel with said relay, and having a second leg that is magnetically saturated when the difference of potential across said relay is of a normal value, a magnetizable leakage member shunting said first leg, and a secondary winding on said member and connected in series with said relay in such manner that the voltage induced in said secondary is 0pposed to the potential applied to the relay from the rails.

1. In combination, a section of railway track, means for supplying alternating current to the rails of the section so that the difference of potential between the rails at a given point is variable, a track relay connected across the rails at said point, a transformer comprising a core having a first leg carrying a primary winding connected in parallel with said relay and having a second. leg that is magnetically saturated at normal values of the difference of potential between the rails at said point, amagnetic leakage member shunting said first leg, and a seconda-ry winding on said member connected in series with said relay.

5. In combination, a section of railway track provided with two track transformers one connected across the rails adjacent each end of the section, means for selectively energizing one or the other of said transformers to create an alternating difference of potential. between the rails, a transformer comprising a core having a first leg carrying a primary Winding which is connected across the rails adjacent one end of the section, and a second leg that is magnetically saturated when the transformer at the other end of the section is energized, a magnetic leakage member shunting; said first leg, a secondary Winding on said leakage member, a track relay connected in series With said secondary Winding, said re- I lay and said secondary being connected in parallel wlth sald prlmary W1nd1ng.

In test-nnony whereof I affix my slgnature.

HOWARD A. THOMPSON. 

